I've translated the subtitles for Troll Bridge for a screening at a local scifi/fantasy con, and I've watched it so many time while working on it so it's pretty much engraved in my mind. So I guess that's my favorite.

From the Sky adaptations, Going Postal and Hogfather are quite good and fun to watch. I guess they didn't have a huge budget so it can look a little cheap in some parts, but the script and acting make up for it (also Going Postal has Claire Foy who is amazing). Colour of Magic is... fine, but not as good. Maybe because it's based on an earlier book. But something feels off with that one.

I never liked the Cosgrove Hall animated movies. They're ugly and surprisingly boring even though they take a lot of the dialog directly from the books.

(not Discworld, but) Johnny and the Bomb mini series is also nice. Not as deep as the book but a fun kids movie. Shame they didn't do the other two.